Comment: 00:40 - 01:54 (01:14)
Source: Annenberg/CPB Resources - Earth Revealed - 22. Wind, Dust and Deserts
Keywords: introduction, "James Sadd", "Death Valley", lake, valley, shoreline, grassland, slope, "pine tree", humid, animal, bison, antelope, horse, pelican, flamingo, climate, glacier, "Ice Age", salt, lakebed, desert, plant, evaporation
Our transcription: Death Valley hasn't always looked like this.
Within the last 100,000 years, a lake 600 feet deep covered this valley floor.
The surrounding shoreline was grassland, and these hill slopes were covered with pine trees.
The mild, relatively humid climate was enjoyed by such diverse animals as bison, antelope, horses, pelicans, and flamingos.
But all this changed about 11,000 years ago, when the Earth's climate began to warm, and the glaciers of the last Ice Age melted back in retreat.
Today the lake is gone, it's been replaced by this salt encrusted dry lakebed.
When the lake disappeared; so did the grasses, and the forest retreated up the mountain slope.
A very different community of plants and animals now inhabit this region.
In short, all of the characteristics of a typical desert.
But Death Valley is not alone, you see this same dramatic change in environment in deserts all over the world.
And this change is the direct result of geologic processes that operate on a global scale.
Geology School Keywords